<div></div><div>Then consider an&nbsp;<b>embedding</b> of the chemical space into the&nbsp;<b>unit sphere of dimension&nbsp;</b><i><b>n</b></i>, (typically,&nbsp;<i>n</i> ~ 300). For example, <a href="https://pubs.acs.org/doi/full/10.1021/acs.jcim.7b00616 " target="_blank">Mol2Vec</a> or Smiles2Vec (<a href="https://arxiv.org/abs/1712.02034" target="_blank">PNNL</a>). Such embedding is analogous to&nbsp;<a href="https://en.wikipedia.org/wiki/Word2vec" target="_blank">Word2Vec</a> in Natural Language Processing. Then we can identify a molecule in the chemical space with its image in the sphere by the embedding, and we can compute the entropy of&nbsp;<i>A</i>&nbsp;with the formula:</div><div></div>